Effects of agricultural residues on TPH concentration and genotoxic and mutagenic activities of a landfarming facility at an oil refinery

Abstract

Industrial and agricultural activities produce large quantities of residues. Bioremediation and the recycling of wastes are alternative techniques that are used to minimize the possible environmental effects caused by improper disposal and ineffective treatments. Landfarming is a bioremediation technology designedto reduce the concentration of organic contaminants in the soil. It has been widely used by refineries to treat the sludge produced during oil refinement. Supplementary treatments, such as adding bulking agents and nutrients to the soil, can be used to accelerate this process. Because of their characteristics, the addition of agricultural residues into soils contaminated with petroleum sludge and its by-products may be an environmentally viable recycling alternative. In this chapter, we evaluated the effects of agricultural residues, rice hulls and sugar cane vinasse, on the total petroleum hydrocarbon (TPH) concentration and genotoxicity and mutagenic activity of soil contaminated with petroleum refinery sludge (landfarming soil). The TPH concentration was measured at the beginning and end of theexperiments, as well as the genotoxic and mutagenic activity of the samples using Allium cepa bioassay. Our results showed that at the beginning ofthe experiments, a high TPH concentration, 17.28 g/kg, and a high genotoxic and mutagenic activity (p<0.05) were detected in soil samples from landfarming site. After 33 days, the TPH concentration in the untreated landfarming soil sample was reduced by 8.77%. In the landfarming soil sample treated with sugar cane vinasse, the TPH concentration decreased by 12.96%, while genotoxic and mutagenic activities were statistically significant (p<0.05). In the landfarming soil sample treated with rice hulls alone or rice hulls combined with sugar cane vinasse, there were significant reductions in the TPH concentration, 46.56% and 51.01%, respectively, and in genotoxicity and mutagenicity (p<0.05) and may be routinely used in the bioremediation of soils contaminated with petroleum sludge. However, due the deleterious effects obtained for landfarming and rice hulls combined with sugar cane vinasse sample, more studies should be conducted with sugar cane vinasse and soil contaminated with petroleum. It is expected that the study can contribute tothe reuse of wastes.